To some image forming apparatuses provided with an image reading portion for reading a document (sheet), a sheet conveying device is fitted. In an image forming apparatus to which a sheet conveying device is fitted, conveyed-document reading can be performed. When a job involving conveyed-document reading is performed, a document is conveyed to an image reading position of the image reading portion by the sheet conveying device. Then, when the document being conveyed passes the reading position, the document is read by the image reading portion.
For example, the sheet conveying device is provided with a tray on which a document is placed, and conveys the document placed on the tray to the reading position. The sheet conveying device is provided with a pick-up roller for pulling the document out from the tray. The pick-up roller rotates by receiving a driving force from a stepping motor. As the pick-up roller touches the document placed on the tray while rotating, the document is pulled out from the tray (for example, see Patent Document 1).